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#1 Last Island Royal Queen of Literature Join Date: May 2005 Location: Forest of Fallen Stars Posts: 7,553 Thanks: 2,411 Thanked 15,791 Times in 4,991 Posts            Physics Paper 2007

FEDERAL PUBLIC SERVICE COMMISSION
COMPETITIVE EXAMINATION FOR RECRUITMENT TO POSTS
IN BPS  17 UNDER THE FEDERAL GOVERNMENT, 2007.

PHYSICS, PAPER - I

TIME ALLOWED: THREE HOURS MAXIMUM MARKS:100

NOTE: (i) Attempt FIVE questions in all including question No. 8 which is compulsory. All questions carry EQUAL marks.
(ii) Extra attempt of any question or any part of the attempted question will not be considered
(iii) Candidate must draw two straight lines (==================) at the end to separate each question attempted in Answer Books.

Q.1. (a) If
α, ß, γ are the angles that vector r=xi+yj+zk makes with the positive directions of the coordinate axes, then show that cos 2 α + cos 2 ß + cos 2 γ = 1 . (6)
(b) Find a such that the vectors 2ij+k, i+2j3k, and 3i+aj+5k are coplanar. (6)
(c) If
Φ =3x2zy2z3+4x3y+2x3y5, then find Div. grad F . (8)

Q.2. (a) State and explain Keplers laws of planetary motion. (12)
(b) A satellite is placed in a circular orbit with a radius equal to one half the radius of the moons orbit. What is its period of revolution in lunar months (the period of revolution of moon)? (8)

Q.3. State Bernoullis theorem and give all necessary conditions. Derive Bernoullis equation for moving fluids. (4,4,12)

Q.4. (a) What is simple harmonic motion (SHM)? Write the equation for SHM and solve it to find its time period. (2,4,8)
(b) A body oscillates with SHM according to equation: (6)
x=(6.12m)cos(8.38 rad/s)t+1.92 rad. Find its time period.

Q.5. (a) What do you understand by diffraction of light? Give all the necessary conditions. Explain diffraction through a single slit and derive an expression for the minimas in the diffraction pattern. (2,4,4,6)
(b) Monochromatic light of wavelength 44lnm falls on a narrow slit On screen 2.16m away, the distance between the second minima and the central maxima is 1.62cm. Find the width of the slit. (4)

Q.6. (a) Explain the terms isothermal and adiabatic processes and calculate the work done in each case. (7,7)
(b) Calculate the work done by an external agent in compressing 1.12 mole of oxygen from a volume of 22.4L and 1.32atm. pressure to 153 L at the same temperature. (6)

Q.7. Write notes on any TWO of the following: (10 each)
(a) Lorentz transformation
(b) Equivalence of mass and energy
(c) Production of low temperature

COMPULSORY QUESTION

8. Write only the correct answer in the Answer Book. Do not reproduce the questions.

(1) A rock is thrown vertically upward with initial speed Vo. Assume a frictional force proportional to the velocity of rock V, and neglect the buoyant force exerted by air. The acceleration of the rock is?
(a) Always equal to g
(b) Equal to g only at the top of the flight
(c) Always less than g
(d) None of these

(2) In circular motion, the quantity mv²/r is:
(a) Momentum
(b) Acceleration
(c) Force
(d) None of these

(3) A ball is dropped from a height h. As it becomes off the floor its speed is 80 percent of what it was just before it hit the floor. The ball will rise to a height of most nearly.
(a) .80 h
(b) .75 h
(c) .64 h
(d) None of these

(4) A force is said to be conservative if:
(a) F.dA=0
(b) F.dr=0
(c) Force must be frictional
(d) None of these

(5) The kinetic energy of a particle of mass m and momentum p is given by
(a) 2m/p
(b) p²/2m
(c) 2m/p²
(d) None of these

(6) Youngs Modulus is the ration between:
(a) Strain and stress
(b) Stress and strain
(c) Strain and longitudinal stress
(d) None of these

(7) In special theory of relativity the Time Dilation applies to:
(a) Atomic clocks only
(b) Mechanical clocks only
(c) Both clocks
(d) None of these

(8) A container has a small hole in bottom. Air can go through this hole, but water cannot. This can be best explained by the statement that:
(a) Water molecules are larger than molecules in the air
(b) Water is more viscous than air
(c) Surface tension of the water prevents it from escaping
(d) None of these

(9) Entropy of universe during any natural process:
(a) Remains constant
(b) Decreases
(c) Increases or remain constant
(d) None of these

(10) For an ideal gas PV=nRT, the SI units of Universal Gas Constant R is:
(a) Joule K-1 mole-1
(b) Newton K-1 mole-1
(c) Watt K-1 mole-1
(d) None of these

(11) If the higher temperature is double than the lower temperature of a Carnots engine, then its efficiency will be:
(a) 30%
(b) 60%
(c) 50%
(d) None of these

(12) The average translational kinetic energy of an atom of a gas is equal to:
(a) (1/2) kT
(b) (3/2) kT
(c) 3kT
(d) None of these

(13) Boltzmann law of distribution of energy among the gas atoms is:
(a) Linear
(b) Exponential
(d) None of these

(14) By increasing the mass of bob of a simple pendulum by 3 times, the time period of the pendulum will:
(a) Increase 3 times
(b) Decrease 3 times
(c) Remains unchanged
(d) None of these

(15) The waves that cannot be plane polarized are:
(b) Sound waves
(c) Infrared light waves
(d) None of these

(16) In sound frequency determines Pitch and in light frequency determines:
(a) Speed
(b) Type of polarization
(c) Colour
(d) None of these

(17) The velocity of electromagnetic wave in free space is given by:
(a) C2 = µo Eo
(b) C½ = µo Eo
(c) C= µo / Eo
(d) None of these

(18) The speed of light in a certain transparent substance is two fifths of its speed in air. The index of refraction of this substance is:
(a) 1.4
(b) 2.0
(c) 2.5
(d) None of these

(19) A thin layer of oil on the surface of water appears coloured because of:
(a) Interference
(b) Polarization
(c) Diffraction
(d) None of these

(20) A man is 10 feet away from a plane mirror. His distance from his image is:
(a) 20
(b) 10
(c) 5
(d) None of these
__________________
The Me you have always known, the Me that's a stranger still.
 The Following 3 Users Say Thank You to Last Island For This Useful Post: aasho (Wednesday, October 10, 2007), aurkn (Sunday, July 20, 2008)
#2 Last Island Royal Queen of Literature Join Date: May 2005 Location: Forest of Fallen Stars Posts: 7,553 Thanks: 2,411 Thanked 15,791 Times in 4,991 Posts            FEDERAL PUBLIC SERVICE COMMISSION
COMPETITIVE EXAMINATION FOR RECRUITMENT TO POSTS
IN BPS  17 UNDER THE FEDERAL GOVERNMENT, 2007.

PHYSICS, PAPER - II

TIME ALLOWED: THREE HOURS MAXIMUM MARKS:100

NOTE: (i) Attempt FIVE questions in all including question No. 8 which is compulsory. All questions carry EQUAL marks.
(ii) Extra attempt of any question or any part of the attempted question will not be considered
(iii) Candidate must draw two straight lines (==================) at the end to separate each question attempted in Answer Books.

Q.1.
Write an expression giving the capacity of parallel plate capacitor and derive an equation giving the energy stored in it. How the capacity changes when it is filled with a dielectric material? (4,10,6)

Q.2.
(a) Explain Amperes circuital law. Use it to find the magnetic field in a
solenoid. (6,8)
(b) A solenoid 1.33cm long and 2.6cm in diameter carries a current of 17.8A. The magnetic field inside the solenoid is 22.4mT. Find the length of the wire forming the solenoid. (6)

Q.3.
(a) Explain the term radioactivity. Write the equation for decay rate and find the expression for half life of radioactive element. How will you find the age of the radioactive sample? (2,3,6,5)
(b) A rock is formed to contain 4.2mg of U and 2mg of Pb. Assume that the rock contained no lead at formation, with all the lead now present arising from the decay of uranium. Find age of the rock. The half life of U is 4.47x10 9 years.(4)

Q.4.
(a) What is thermionic emission? Name and explain some of its important applications. (4,6)
(b) How can you use triode as detector in radio wave receivers? (10)

Q.5.
(a) What is P-N junction? Explain its working in forward and reverse biasing conditions. (4,8)
(b) Draw bridge circuit for rectification and explain how it rectifies an AC. (8)

Q.6.
(a) Explain de Broglie hypothesis and write an equation giving de Broglie wavelength. Give an experiment to prove it. (4,4,6)
(b) Calculate the de Broglie wavelength of an electron whose kinetic energy is 120eV. (6)

Q.7.
Write notes on any TWO of the following: (10 each)
(a) Paulis exclusion principle
(b) Zeeman effect
(c) Elementary particles

COMPULSORY QUESTION

Q.8. Write only the correct answer in the Answer Book. Do not reproduce the question.
(20)

(1) Four equal charges of +10 m C are placed at four corners of a square. The electric intensity at the center of the square is:
(a) Zero NC1
(b) 5 NC1
(c) 2.5 NC1
(d) None of these

(2) A current of 200mA is flowing in a conductor. How many electrons are passing
through it in one minute?
(a) 75X1020
(b) 750X1018
(c) 75X1015
(d) None of these

(3) A particle having charge q and moving with velocity v enters in the magnetic field
B at right angles to the field. The force acting on the particle is:
(a) Bqv
(b) Bq/v
(c) Bv/q
(d) None of these

(4) Maximum voltage is induced in the conductor when it moves in the magnetic field
in the direction:
(a) Perpendicular to the field
(b) Parallel to the field
(c) At an angle of 45°to the field
(d) None of these

(5) Lines of magnetic field have the property:
(a) Lines do not terminate at the magnetic poles
(b) Lines continue to pass through the bar magnet
(c) Both (a) and (b)
(d) None of these

(6) Bohr atomic theory cannot explain:
(a) The intensity of spectral lines
(b) Atomic interaction
(c) Both (a) and (b)
(d) None of these

(7) Electron-positron annihilation gives out:
(a) Alpha-rays
(b) Beta-rays
(c) Gamma-rays
(d) None of these

(8) In photoelectric effect the energy of the photon in excess of work function of the
metal is:
(a) Absorbed by the metal
(b) Reflected back
(c) Taken by the emitted electron
(d) None of these

(9) The probability that a particle will leak through a potential barrier is known as:
(a) Tunnel effect
(b) Zeeman effect
(c) Quantum effect
(d) None of these

(10) A narrow wave group helps to determine accurately, the:
(a) Position of a particle
(b) Momentum of a particle
(c) Both (a) and (b)
(d) None of these

(11) The relationship between the atomic number (A), mass number (M), and number of neutrons (N) is:
(a) A=MN
(b) A=MN
(c) A=NM
(d) None of these

(12) In 1896, the radioactivity was discovered by:
(a) Curies
(b) Becqueral
(c) Dalton
(d) None of these

(13) The emission of one alpha particle from the nucleus of an atom produces a change of:
(a) 1 in atomic number
(b) 1 in atomic mass
(c) 2 in atomic number
(d) None of these

(14) Fermions have half integral spin and:
(a) Obey exclusion principle
(b) Do not obey exclusion principle
(c) May or may not obey exclusion principle
(d) None of these

(15) The conversion of atoms of a given element into atoms of a different isotope or of a different element, as in radioactive disintegration or by nuclear bombardment, is
known as:
(b) Transmutation
(c) Transformation
(d) None of these

(16) According to Band theory of solids, free electrons are present in:
(a) Valance band
(b) Conduction band
(c) Both (a) and (b)
(d) None of these

(17) The forbidden energy gap of a material is 0.01eV, the material is:
(a) Semiconductor
(b) Insulator
(c) Conductor
(d) None of these

(18) In a semiconductor which is heavily doped with arsenic, electrons are also called:
(a) Majority carriers
(b) Minority carriers
(c) Fast carriers
(d) None of these

(19) Among the vacuum tube devices, the suppresser grid is present only in:
(a) Triode
(b) Tetrode
(c) Pentode
(d) None of these

(20) In a p-n-p transistor, the emitter-base junction is always forward biased while the collector-base junction is reversed biased. As a result, any changes in base current will effect the:
(a) emitter current
(b) base current
(c) collector current
(d) None of these
__________________
The Me you have always known, the Me that's a stranger still.
 The Following 2 Users Say Thank You to Last Island For This Useful Post: maria khan (Friday, October 12, 2007), Saqib Ijaz (Saturday, July 30, 2011)
#3 very special 1 Senior Member Join Date: Dec 2010 Location: dream land,where eagles live Posts: 441 Thanks: 484 Thanked 286 Times in 195 Posts    objective ans
1= a
2=c
3=dont knw
4 =a
5=b
6=b
7=c
8=c
9=c
10= a
11=c
12=b
13
14=d
15=b
16=a
17=
18=
19=a
20=b
i am not confirm about ans

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